Fuel supply system for internal combustion engines

ABSTRACT

A fuel supply system for internal combustion engines comprising an engine rpm function control circuit for controlling fuel flow in conformity with the rpm of the engine, a manifold boosted pressure function control circuit for controlling fuel flow in conformity with the boosted pressure in the manifold, a summing impact modulator for causing fuel controlled by said two circuits to be injected, and a transverse impact modulator for supplying air in amounts such that proper proportions of air and fuel can be obtained in conformity with the boosted pressure.

United States Patent 1 51 3,695,245 Ishida [4s] Oct. 3, 1972 [54] FUELSUPPLY SYSTEM FOR 3,556,063 1/ 1971 Tuzson ..20l/D[G. 69 INTERNALCOMBUSTION ENGINES 3,577,964 5/1971 Lazar ..201/DlG. 69 72 InventTakash- Ishid hi, J 3,586,024 TLlZSOIl A 1 I f mac 3,587,543 6/1971Sulich ..20l/36 A Asslgnw u Kogyo Tokyo, 3,590,840 7/1971 l'lyer..20l/36 A apan 22 Filed; No 23, 197 Primary Examiner-Laurence M.Goodridge Assistant Examiner-Ronald B. Cox [21] Appl' 91618Attorney-McGlcw and Toren [30] Foreign Application Priority Data [57]ABSTRACT Nov. 22, 1969 Japan ..44/938l4 A fuel supply system forinternal combustion engines 1 comprising an engine rpm function controlcircuit for 140 123/ l 19 R, l2 controlling fuel flow in conformity withthe rpm of the v 140 R engine, a manifold boosted pressure functioncontrol [5 Clcircuit for controlling fuel flow in conformity the [58] mof search-12y l 19 140 36 boosted pressure in the manifold, a summingimpact 123/261 F L1 69 modulator for causing fuel controlled by said twocir- 6 f cuits to be injected, and a transverse impact modula- [5 1 Reerences Cned tor for supplying air in amounts such that proper pro-UNITED STATES PATENTS portions of air and fuel can be obtained inconformity with the boosted pressure. 3,461,892 8/1969 Boothe ..201/DlG.69 3,548,794 12/ 1970 Lazar ..201/DlG. 69 5 Claims, 12 Drawing FiguresPATENTEDHIIIB I912 3.695.245

SHEET B [If 7 Bias Vent INVENTOR.

70k 407 .zM/M

PATENTEDBM 19w SHEEI 7 BF 7 air T IMF Vent f air Vent

Boost FIG.12

Drain Drain Bias INVIQZNTOR. 73W 0060 1204/00 iffMA/t/J FUEL SUPPLYSYSTEM FOR ERNAL COMBUSTION ENGINES This invention relates to fuelsupply systems for intemal combustion engines. More particularly, theinvention deals with a fuel supply system for internal combustionengines which employs fluid elements in the fuel injection controlcircuit to ensure that fuel injection positively takes place during eachsuction stroke of the engine.

Heretofore, many fuel supply systems for internal combustion engineshave been known wherein the valve is opened and closed by a mechanicalor electric system for injecting fuel into the engine manifold through asmall aperture. In a mechanical fuel supply system, the number ofrevolution per minute (hereinafter referred to as the rpm) of theengine, the opening of the aperture of the air valve and the internalpressure in the manifold are detected and the values obtained areapplied to a mechanical operation device for actuating the injectionnozzle as shown in FIG. 1. In an electric fuel supply system, the valuesobtained by detecting the rpm of the engine and the boosted pressure inthe manifold are applied to an electric operation circuit for openingand closing the valve for injecting fuel. These systems of the prior artare not without disadvantages.

When fuel supply is controlled mechanically, it is not possible toeffect injection of fuel satisfactorily irrespective of the conditionsof the load. Misoperation may result from vibration and noise ofexternal electromagnetic waves when the electric control of fuel supplyis carried out.

Accordingly, an object of the present invention is to provide a fuelsupply system for internal combustion engines which employs fluidelements in the fuel injection control circuit to ensure that fuelinjection positively takes place during each suction stroke of theengine.

Another object of the invention is to provide a fuel supply system forinternal combustion engines wherein fluid elements having no movableparts are provided in the injection nozzle portion and a part of theoperation device for controlling the amount of fuel to be injected sothat the fuel injected during each suction stroke of the engine maybe inamounts such that correct proportions of fuel and air can be obtained.

The present invention is based on the following technical concept.Generally, the fuel flow characteristics of any reciprocating engine arerepresented by the factors which are the rpm of the engine and theboosted pressure in the manifold. Accordingly, fuel consumption may beindicated as the amount of fuel consumed in terms of the rpm of theengine using the boosted pressure as a parameter as shown-in FIG. 4 oras the amount of fuel consumed in terms of the boosted pressure usingthe rpm of the engine as a parameter as shown in FIG. 5. In either case,the amount of fuel consumed covers all the operation conditions of thevehicle. From this, it naturally follows that, if a function of the rpmof the engine and a function of the boosted pressure in the manifold areprepared, then it is possible to cover fuel consumption at all thevehicle speeds under all operating conditions.

In accordance with the aforementioned concept, the rpm of the engine isconverted into a pneumatic pressure in the present invention, and thepneumatic pressure detected and the boosted pressure in the manifold areapplied to an operation device which is provided with fluid elements soas to operate a fuel injection device.

According to this invention, there is provided a fuel supply system forinternal combustion engines which comprises an engine rpm functioncontrol circuit for controlling fuel flow in conformity with the rpm ofthe engine, a manifold boosted pressure function control circuit forcontrolling fuel flow in conformity with the boosted pressure in themanifold, 2'. summing impact modulator for causing fuel controlled bysuch two circuits to be injected, and a transverse impact modulator forsupplying air in amounts such that proper proportions of air and fuelcan be obtained in conformity with the boosted pressure.

The fuel supply system according to this invention constructed asaforementioned has many advantages. According to the invention, the rpmof the engine, and the boosted pressure in the manifold are detected interms of pneumatic pressures and the operation device is driven by thepneumatic pressures, so that it is possible to obtain optimum air-fuelmixtures over a wide range of vehicle speeds under all engine operationconditions. The fuel supply system according to this invention is freefrom the influences of vibration and noise. Besides, atomization of fuelcan be effected satisfactorily.

' Additional objects of this invention as well as features andadvantages thereof will become evident from the description set forthhereinafter when considered in conjunction with the accompanyingdrawings, in which:

FIG. 1 and FIG. 2 are block diagrams of conventional fuel supply systemsfor internal combustion engines;

FIG. 3 is a block diagram of thefuel supply system according to thisinvention;

FIG. 4 is a diagrammatic representation of fuel consumption in terms ofthe rpm of the engine using the boosted pressure as a parameter;

FIG. 5 is a diagrammatic representation of fuel consumption in terms ofthe boosted pressure using the rpm of the engine as a parameter;

FIG. 6 is a schematic view showing the arrangement of various parts ofone embodiment of the fuel supply system shown in FIG. 3;

FIG. 7 is a sectional view, on an enlarged scale, of the fuel injectionnozzle portion of the system of FIG. 6;

FIG. 8 is a schematic view showing the arrangement of various parts ofanother embodiment of the fuel supply system shown in FIG. 3;

FIG. 9 is a view showing a modification of FIG. 6 in which the partsfollowing the one shot circuit are changed;

FIG. 10 and FIG. 11 show examples in which a proportioning element and afluid element of the collision type are used respectively in place ofthe pneumatic pressure control valve; and

FIG. 12 shows another modification in which engine rpm function controlis effected by pneumatic pressure alone.

Embodiments of this invention will now be explained with reference tothe accompanying drawings. FIG. 6 shows a first embodiment of the fuelsupply system according to this invention which comprises an engine rpmfunction control circuit ERF, manifold boosted pressure function controlcircuit MBF, summing impact modulator SIM for causing fuel to beinjected in conformity with the outputs of the two aforementionedcircuits, and a transverse impact modulator TIM for supplying air inamounts such that correct proportions of air and fuel can be obtained inconformity with the boosted pressure.

The engine rpm function control circuit ERF detects the number ofrevolution per minute of a rotary shaft 20 connected to the engine crankshaft and the like and controls fuel flow in accordance with the rpm ofthe engine. The manifold boosted pressure function control circuit MBFcontrols fluid flow in terms of the boosted pressure in a manifold usingthe boosted pressure as an input. The manifold 10 is provided with athrottle valve 11 on the opening side and an inlet valve 12 on theengine side, and a boosted pressure detection aperture 13 is formed inthe wall of the manifold 10 in a position below the throttle valve 11.The summing impact modulator SIM is attached to the manifold 10 in theform of an injection element IE.

ENGINE RPM FUNCTION CONTROL CIRCUIT This circuit ERF comprises agovernor 21, pneumatic pressure control valve CV, one shot circuit OSCand trigger means TM.

A fly-weight 24 which is brought to an upright position while the rotaryshaft 20 rotates is pivotally supported by a pin 23 attached to a partof a disc 22. The flyweight 24 includes an arm 25 which is adapted toengage a forward end of a valve stem 26 of the control valve CV.

The valve stem 26 extends through the interior of a casing of thecontrol valve CV which is divided into two chambers 28 and 29 by a valveseat 32 cooperating with a needle 27 attached to a rear end of the valvestem 26. An air supply port 30 is formed in the wall of one chamber 28and an air exhaust port 31 is formed in the wall of the other chamber29. The valve stem 26 extending through the valve casing is normallyurged by the biasing force of a spring 33 to move in a direction suchthat the forward end of the valve stem 26 is brought into engagementwith an end surface of the arm 25 and the needle 27 is seated at thevalve seat 32.

If the valve stem 26 moves to the right in FIG. 6 against the biasingforce of the spring 33, the aperture of the control valve CV will besuccessively increased in cross-sectional area. Accordingly, adischarged air flow 0, proportional to the rpm of the engine is suppliedto the one shot circuit OSC.

The one shot circuit OSC comprises two fluid elements F D and FD whichhave no movable parts. The output 0 of the control valve CV is appliedto the one shot circuit OSC as an input thereto and the deflected output0 of the first stage fluid element FD is introduced into a control portof the second stage fluid element F D whose output is applied through acheck valve V to an injection port [n of the summing impact modulatorSIM subsequently to be described.

Signals from trigger means TM are introduced into the first stage fluidelement FD The trigger means TM comprises a cam disc 34 formed with aplanar surface which is inclined with respect to the direction ofrotation of the cam disc, an air jet supply duct 35 through which an airjet stream is supplied to impinge on the inclined planar surface, and anoutput duct 36 through which one impulse output signal is provided foreach revolution of the cam disc 34.

The number of revolution n of the cam disc 34 can be expressed asfollows:

n kn In the case of four cycle engines.

= kn In the case of two cycle engines.

where n is the number of revolution of the governor 21 and n k n n beingthe number of revolution of the engine crank shaft and k being theconstant. Thus, as the cam disc rotates, trigger signals of a definitecycle are applied to the first stage fluid element FD as a basis forengine rpm function control.

A fuel supply controlled by the manifold boosted pressure functioncontrol circuit MBF is delivered to a main injection port of the secondstage fluid element FD and the periodical output 0 of the first stagefluid element FD is applied to the second stage fluid element FD whichproduces a deflected output.

MANIFOLD BOOSTED PRESSURE FUNCTION CONTROL CIRCUIT This circuit MBFcomprises a pneumatic pressure control valve FV and fuel flow controlvalve FV connected in series with each other.

' The pneumatic pressure control valve FV and fuel control valve FV eachincludes a valve casing 37 in which a bellows 38 and a needle 39cooperating with a valve seat 40 are mounted. The valve casing 37 isformed on the wall on the bellows side with an input port 41 and on thewall on the needle side with an output port 42. An air supply port 43 isformed in a side wall of the first stage valve FV and a fuel supply port44 is formed in a side wall of the second stage valve FV The pneumaticpressure supplied through the detection aperture 13 of the manifold 10is introduced into the input port 41 of the first stage valve FV toactuate the bellows 38 and produce an output which is applied to theinput port 41 of the second stage valve F V An output 0 of the secondstage valve FV is applied to an injection port in of the summing impactmodulator SIM.

The second stage valve FV varies the aperture formed between the valveseat 40 and needle 39 as the bellows 38 expands and contracts inconformity with the magnitude of the outputs of the first stage valve FV so as to control fuel flow therethrough after the fuel is suppliedthrough the fuel supply port 44.

Part of the output 0 of the second stage valve FV is passed through abranch line to a main injection port of the second stage fluid element FD of the one shot circuit referred to above.

TRANSVERSE IMPACT MODULATOR This circuit TIM is intended to supply airin amounts such that proper proportions of air and fuel in proportion tothe boosted pressure can be provided.

A line 61 branching from the line connecting the boosted pressuredetection aperture 13 to the first stage valve FV referred to above isconnected to a control port 50 of a proportioning element PFD. Theoutput of the proportioning element PFD is transmitted to the modulatorcircuit TIM whose output is supplied through a check valve V mounted ona line 62 to the injection port in of the summing impact modulator SIMtogether with the output of the second stage fluid element FD suppliedthrough a check valve V Part of the output of the modulator circuit TIMis passed through a check valve V, on a line 63 and supplied to theinjection port in of the summing impact modulator SIM together with theoutput of the second stage valve FV which is passed through a checkvalve V SUMMING IMPACT MODULATOR This circuit SIM is provided with adrain in addition to the injection ports in and in referred to above.The circuit SIM is formed into an injection element IE to be built inthe manifold as shown in FIG; 7. It will be seen that the injectionports in, and in have apertures which are juxtaposed to each other witha small clearance being interposed therebetween, and that a cover. 52 isprovided around the injection port in to which a drain 51 is connected.

OPERATION OF THE SYSTEM The operation of the fuel supply systemaccording to this invention will now be explained. In FIG. 6, thegovernor 21 rotates at a rate. proportionate to the rate of revolutionof the engine and actuates the fly weight 24 for regulating thepneumatic pressure control valve CV.

The output of the control valve CV is supplied to the one shot circuitOSC as its input while the one shot circuit is triggered by pulse-likepneumatic pressure signals from the trigger means TM.

The cam disc 34 for producing trigger signals produces one trigger pulsefor each one complete revolution. Therefore, the cam disc is set suchthat it rotates at a number of revolution which is one half the numberof revolution of the crank shaft of four-cycle engines and at the samenumber of rotation as the crank shaft of two-cycle engines.

The output cycle of the one shot circuit OSC is increased as its supplypressure increases. The output characteristics of the engine rpmfunction control circuit ERF comprising the governor 21, pneumaticpressure control valve CV, one shot circuit OSC and trigger means TM aresuch that by selecting a suitable shape for the needle 27 of the controlvalve CV it is possible to draw curves of fuel consumption as shown inFIG. 4. An engine rpm function can be obtained in this way.

On the other hand, the boosted pressure in the manifold is led to thepneumatic pressure control valve FV, including the bellows and needle.The needle 39 of the pneumatic pressure control valve FV is set suchthat the output of the control valve FV, is reduced in value when theabsolute value of the boosted pressure is increased, and increased whenthe absolute value of the boosted pressure is reduced. The pneumaticpressure regulated in this way is supplied to the fuel flow controlvalve FV to which fuel is supplied. The fuel flow control valve FV isconstructed such that by selecting a suitable shape for the needle 39 itis possible to draw curves of fuel consumption as shown in FIG. 5. Amanifold boosted pressure function can be obtained in this way.

Thus, the engine rpm function and manifold boosted pressure function areproduced, and part of the output of thefuel flow control valve W istransmitted to the one shot circuit OSC as a supply of power.

Part of the output of the fuel control valve FV, is transmitted throughthe check valve V to the summing impact modulator SIM provided in themanifold 10 as a supply of power thereto. In FIG. 6, this supply ofpower is shown as being in the form of a steady current and not beingpulse-like. On the other hand, the output of the one shot circuit OSC istransmitted through the check valve V to the summing impact modulatorSIM as a supply thereto. The supply of power passed through the checkvalve V, is set to enter the summing impact modulator from the side onwhich its output port is provided. Accordingly, the supply of power tothe injection port in shown in FIGS. 6 and 7 is in pulse form. The checkvalve V is an element which is intended to prevent reverse flow ofpneumatic pressure to the one shot circuit which might otherwise becaused by the supply of power delivered in the form of a steady streamto the injection port in when there is no output of second stage fuelelement FD Because of this arrangement, the injection port in, does notconstitute a so-called impact surface when no pressure is applied to theinjection port in and fuel is drained away through the output port ofthe summing impact modulator SIM. The fuel is returned to a fuel tank orfuel pump (not shown).

It will thus be seen that the summing impact modulator SIM provided inthe manifold 10 constitutes an impact surface by the output of the oneshot circuit OSC for injecting fuel into the manifold 10. The intervalof time in which fuel injection takes place may vary depending on therpm of the engine and the pressure under which fuel is injected may varydepending on the boosted pressure. The interval of time in which fuelinjection takes place can be freely selected by suitably setting the camdisc 34 of the trigger means TM.

The lines 64 and 65 can be constructed such that, when the absolutevalue of the boosted pressure in the manifold exceeds a certain level,there is no output of the fuel flow control valve FV At the same time,air is supplied to the summing impact modulator SIM in the manifold 10in the form of a steady current and not in pulse form.

By controlling the input to the one shot circuit OSC by suitablyreducing the boosted pressure, the output of OSC can be made to be ininverse proportion to the absolute value of the boosted pressure. Theoutput of the transverse impact modulator TIM is supplied to the summingimpact modulator SIM in the manifold 10 through the check valve V Byselecting a suitable spring for the check valve V it is possible tosupply air to the summing impact modulator SIM when the absolute valueof the boosted pressure exceeds a certain level. It will thus be seenthat, when the vehicle is coasting, air injection takes placesimultaneously as the supply of fuel is cut, thereby preventingcontamination of atmosphere by the exhaust of incompletely conbustedfuel.

In mechanical fuel injection systems of the prior art, the mechanicaloperation device, injection nozzle and the like require high precisionmachining. Yet, it is not possible to effect fuel injection in an idealmanner by conventional systems when fuel flow is low in rate, such aswhen the engine is idling. In some cases, the stability of engineoperation is lower than that of carbureter.

Electric systems of the prior art are disadvantageous in thatmisoperation of operation circuit may result from vibration, abnormalengine temperatures and electromagnetic wave noise. In electric systems,the injection nozzle portion requires no less high precision machiningthan in mechanical systems.

In the present invention, ordinary (not precise) machine finishes of theparts are tolerated, and the parts are impervious to the influences ofvibration, heat, electromagnetic wave and the like. The mechanism ofcutting of fuel when the vehicle is coasting is very much simpler in thefuel supply system of this invention than in the conventional fuelsupply system using a carbureter. This invention makes it possible toprovide correct proportions of fuel and air by utilizing an engine rpmfunction of normal operation and a manifold boosted pressure function incombination with each other.

FIG. 8 shows another embodiment of the invention in which the summingimpact modulator SIM serving as an injection element in the embodimentshown in FIG.

6 is replaced by the transverse impact modulator TIM.

The operation of this modulator is similar to that of the modulator ofFIG. 6 except for the operation of the injection element. When thetransverse impact modulator TIM is used as an injection element, asupply of fuel or the output of the fuel control valve FV is passedthrough lines 67 and 68 and applied to-the injection ports in and inwhile the output of the one shot circuit OSC is passed through a line 69and applied to an injection port in (which corresponds to the inlet portof the transverse impact modulator TIM shown in FIG. 6), so that fuelinjection may take place as the flow of fuel to the injection port in isdisturbed.

FIG. 9 shows a modification of the embodiment shown in FIG. 6 in whichthe one shot circuit OSC and the mechanisms that follow it are changed.In this modification, valves V V V and V, are set such that fuel iscaused to flow to the injection ports in and in of the summing impactmodulator SIM only when fuel injection takes place and air is drawn bys'uction when fuel injection does not take place.

In the modification shown in FIG. 10, the pneumatic pressure controlvalve F V, of the embodiment shown in FIG. 6 is replaced by aproportioning element PFD. The boosted pressure in the manifold issuitably reduced and led to one control port of the proportioningelement PFD whose output is supplied to the inlet in of the fuel controlvalve F V This arrangement permits to replace the needle and bellows byan element having no movable parts.

FIG. 11 shows a modification in which the air pressure control valve FVof the embodiment shown in FIG. 6 is replaced by the transverse impactmodulator TIM instead of the proportioning element.

FIG. 12 shows a modification in which fuel of boosted pressure functionis supplied only to the supply port in of the summing impact modulatorSIM while the engine rpm function is operated by air, and pneumaticsignals are supplied to the supply port in of the modulator SIM, so thatan impact surface of fuel and 8. aircanbefo ed in the manifold.

From the oregomg description, it WI" be appreciated that according tothe present invention injection of fuel is controlled not by mechanicalmeans but by the collision between fuel and fuel or fuel and air. Thisarrangement is effective to bring about atomization of fuel in asatisfactorymanner and thereby increase efiiciency of combustion offuel, making it possible to economize on fuel and reduce the amount ofnoxious materials in the exhausts. The use of the fluid elements permitsto reduce production cost of the fuel supply system according to thisinvention as compared with fuel injection systems of the prior art.Besides, the fuel supply system according to this invention operatespositively and is reliable in performance.

What I claim is:

l. A fuel supply system for internal combustion engines comprising anengine rpm function control circuit for controlling fuel flow inconformity with the rpm of the engine, a manifold boosted pressurefunction control circuit for controlling fuel flow in conformity withthe boosted pressure in the manifold, a summing impact modulator forcausing fuel controlled by said two circuits to be injected, and atransverse impact modulator for supplying air in amounts such thatproper proportions of air and fuel can be obtained in conformity withthe boosted pressure.

2. A fuel supply system as defined in claim 1 in which said engine rpmfunction control circuit comprises a governor responding to the rpm ofthe engine, a pneumatic pressure control valve, a trigger mechanism, oneshot circuit, and trigger means.

3. A fuel supply system as defined in claim 1 in which said manifoldboosted pressure function control circuit comprises a pneumatic pressurecontrol valve and a fuel flow control valve connected in series witheach other.

4. A fuel supply system as defined in claim 1 in which said summingimpact modulator has two injection ports and a drain.

5. A fuel supply system for an internal combustion engine having acrankshaft and an intake manifold with a pressure detection aperture,comprising:

an engine rpm function control circuit including a governor responsiveto the engine crankshaft, an air pressure control valve responsive tothe governor, and-a one-shot circuit responsive to air pressure from theair pressure control valve;

a manifold boosted pressure function control circuit including an airpressure control valve responsive to pressure from the detectionaperture in the intake manifold, and a fuel flow control valve connectedin series with said pressure control valve;

a boosted pressure detection circuit including a proportioning elementconnected to a line bypassed from the boosted pressure detection circuitand a transverse impact modulator connected to the output side of saidproportioning element; and

a summing impact modulator injection element including a fuel injectionport and a fuel-air injection port for connecting an output of theone-shot circuit and the boosted pressure detection circuit.

1. A fuel supply system for internal combustion engines comprising anengine rpm function control circuit for controlling fuel flow inconformity with the rpm of the engine, a manifold boosted pressurefunction control circuit for controlling fuel flow in conformity withthe boosted pressure in the manifold, a summing impact modulator forcausing fuel controlled by said two circuits to be injected, and atransverse impact modulator for supplying air in amounts such thatproper proportions of air and fuel can be obtained in conformity withthe boosted pressure.
 2. A fuel supply system as defined in claim 1 inwhich said engine rpm function control circuit comprises a governorresponding to the rpm of the engine, a pneumatic pressure control valve,a trigger mechanism, one shot circuit, and trigger means.
 3. A fuelsupply system as defined in claim 1 in which said manifold boostedpressure function control circuit comprises a pneumatic pressure controlvalve and a fuel flow control valve connected in series with each other.4. A fuel supply system as defined in claim 1 in which said summingimpact modulator has two injection ports and a drain.
 5. A fuel supplysystem for an internal combustion engine having a crankshaft and anintake manifold with a pressure detection aperture, comprising: anengine rpm function control circuit including a governor responsive tothe engine crankshaft, an air pressure control valve responsive to thegovernor, and a one-shot circuit responsive to air pressure from the airpressure control valve; a manifold boosted pressure function controlcircuit including an air pressure control valve responsive to pressurefrom the detection aperture in the intake manifold, and a fuel flowcontrol valve connected in series with said pressure control valve; aboosted pressure detection circuit including a proportioning elementconnected to a line bypassed from the boosted pressure detection circuitand a transverse impact modulator connected to the output side of saidproportioning element; and a summing impact modulator injection elementincluding a fuel injection port and a fuel-air injection port forconnecting an output of the one-shot circuit and the boosted pressuredetection circuit.